Dental arch spatial changes after premature loss of first primary molars: a systematic review of controlled studies

Studies investigating dental arch spatial changes following first primary molar premature loss are controversial regarding clinical significance. The purpose of this review was to systematically investigate the relevant literature. Controlled studies investigating changes before and after premature loss of first primary molars were searched in various databases. Split-mouth design studies were considered eligible for inclusion. The risk of bias was judged according to ADA Clinical Practice Guidelines. Only two analyzable split-mouth studies on mandibular first primary molar loss were identified. Space loss in the extraction side was greater at 2, 4, 6 and 8-month follow-ups, reaching a −1.5 mm difference in the final examination (95% Confidence Interval: −2.080 to −0.925; p = 0.000; random effects model). Studies were judged to be at unclear risk of bias. The amount of space decrease after premature loss of first primary molars may have management implications under certain circumstances. Comprehensive assessment of the various characteristics of each patient should precede management decisions in individual cases.